Disazo dyes containing at least one sulfo group and at least two basic or cationic groups

ABSTRACT

Compounds of the formula ##STR1## wherein F is the residue of a monoazo or disazo compound, 
     each X is independently --NR 2  --Q--NR 3  R 4  or --NR 2  --Q--N.sup.⊕ R 5  R 6  R 7 , 
      wherein 
     Q is linear or branched C 2-6  alkylene, 
     R 2  is hydrogen or C 1-4  alkyl, 
     each of R 3 , R 4 , R 5  and R 6  is independently hydrogen; C 1-6  alkyl; C 2-6  alkyl substituted by hydroxy or cyano; C 1-3  alkyl substituted by phenyl or substituted phenyl having 1 to 3 substituents selected from chloro, C 1-4  alkyl and C 1-4  alkoxy; C 5-6  cycloalkyl or C 5-6  cycloalkyl substituted by 1 to 3 C 1-4  alkyl groups, with the proviso that neither R 5  nor R 6  can be hydrogen, or 
     R 3  and R 4  or R 5  and R 6  taken together and with the nitrogen atom to which they are joined form a 5- or 6-membered ring containing at most one further hetero atom, and 
     R 7  is C 1-4  alkyl or benzyl, 
     each Z 1  is independently --CO--, --SO 2  -- or ##STR2##  wherein R 1  is hydrogen or C 1-4  alkyl, and 
     Y is chloro, hydroxy, amino or an aliphatic or aromatic amino group, 
     each Z 2  is independently ##STR3##  wherein R 1  is hydrogen or C 1-4  alkyl, 
     m is 1 or 2, 
     n is 0-4, and 
     p is 0-3, 
     with the proviso that n+2p≧m+1, the Z&#39;s are carbonyl, sulfonyl or triazine bridging groups and (n+2p)≧m+1 so that there is an excess of basic or cationic groups, are useful as dyes for paper, leather and cellulosic fibres.

This application is a division of application Ser. No. 31,781, filed Apr. 20, 1979 and now U.S. Pat. No. 4,273,707.

This invention relates to azo dyes containing sulphonic acid groups and also basic and/or cationic groups.

The invention provides compounds of formula I ##STR4## in which F is the residue of a mono- or dis-azo compound;

each Z₁, independently, is a divalent group of the formula --CO--, --SO₂ -- ##STR5## in which Y is Cl, OH, NH₂ or an aliphatic or aromatic amino group,

and R₁ is hydrogen or C₁₋₄ alkyl;

each Z₂, independently, is a trivalent group of the formula ##STR6## in which R₁ is as defined above; each X, independently, is a basic group --NR₂ --Q--NR₃ R₄ or a cationic group --NR₂ --Q--N.sup.⊕ R₅ R₆ R₇,

in which

R₂ is hydrogen or C₁₋₄ alkyl,

Q is linear or branched C₂₋₆ alkylene,

R₃ and R₄ are independently hydrogen, unsubstituted C₁₋₆ alkyl, C₂₋₆ alkyl substituted by hydroxy or CN, C₁₋₃ alkyl substituted by phenyl which is unsubstituted or substituted by up to 3 substituents selected from chlorine, C₁₋₄ alkyl and C₁₋₄ alkoxy, or C₅₋₆ cycloalkyl unsubstituted or substituted by up to 3 C₁₋₄ alkyl groups

or R₃ and R₄, together with the N atom to which they are attached, form a 5- or 6-membered saturated heterocyclic ring, which may contain one further hetero atom,

R₅ and R₆ may independently have any of the above significances of R₃ and R₄ other than hydrogen,

R₇ is C₁₋₄ alkyl or benzyl;

m is 1 or 2,

n is 0 or an integer from 1 to 4, and

p is 0 or an integer from 1 to 3,

whereby (n+2p)≧m+1.

In the compounds of formula I, the m sulphonic acid groups may react with the X groups to form internal salts of the type (XH).sup.⊕ SO₃.sup.⊖ or X.sup.⊕ SO₃.sup.⊖. The compounds of formula I have more basic and/or cationic groups than sulphonic acid groups, and the additional basic and/or cationic groups may form external salts, thus rendering the compounds water-soluble.

In the residue of a mono- or dis-azo compound represented by F, the diazo component radical may belong to the aromatic carbocyclic or aromatic heterocyclic series, as for example the aniline, aminonaphthalene, aminodibenzofuran or benzothiazolyluminophenyl series, the aniline series being preferred. The terminal coupling component radical preferably belongs to the naphthalene series and is preferably derived from 1-naphthol-3- or -4-sulphonic acid or a derivative thereof, particularly 6-amino-1-naphthol-3-sulphonic acid or a derivative formed by reaction at the amino group thereof.

In residues of disazo compounds, the central component radical preferably belongs to the phenylene, naphthylene or tetrahydronaphthylene series, more preferably the 1,4-phenylene series.

F may also for example be the residue of a disazo compound in which the coupling component radicals or diazo component radicals of two monoazo compounds are connected together directly or through a bridging group.

The sulphonic acid groups may be located in the diazo and/or in the coupling component radical and optionally also in the central component radical or bridging group. Preferably, however, the coupling component radical carries at least one sulphonic acid group, more preferably one only.

The (n+2p) X groups, which may be the same or different, are connected through the polyvalent groups Z₁ and Z₂ to the diazo component radical and/or the terminal coupling component radical of the group F. Where Z₁ is Z₁ ', i.e. --CO-- or --SO₂ --, then the group --Z_(1') 13 X (for convenience referred to as X_(I)) is preferably located on the diazo component radical. For a diazo component radical of the aniline series, two groups X_(I) are preferably attached as in formula IIa or IIb ##STR7## in which the groups X_(I) are preferably identical, and preferably there is no, or only one, further substituent on the benzene ring.

The groups ##STR8## together represented for convenience as X_(II), in which X₁ " is the divalent group ##STR9## are preferably located on the diazo component radical and/or the terminal coupling component radical, it being particularly preferred that the latter contains at least one such group. For a diazo component of the aniline series, formulae IIIa and IIIb are preferred. ##STR10## In formula IIIa, one further substituent may be located preferably at the 2-, 4- or 6-position or two further substituents may be located preferably at the 2,5-positions. In formula IIIb there is preferably one additional substituent, which may be in any position.

When the terminal coupling component radical carries a group X_(II), this is preferably derived from a compound of formula IV ##STR11## in which the arrow shows the position at which coupling occurs.

The alkylene group Q is preferably linear and more preferably is an ethylene or propylene group.

Where groups R₁ and R₂ are alkyl, they are preferably methyl. R₁ and R₂ are preferably R₁ ' and R₂ ', where R₁ ' and R₂ ' are independently methyl or hydrogen, more preferably hydrogen.

The groups R₃ and R₄ are preferably identical. When they are C₁₋₆ alkyl groups, they may be straight-chain or branched and are preferably C₁₋₄ alkyl, more preferably methyl or ethyl. Cyano- and hydroxy-substituted C₂₋₆ alkyl groups are preferably substituted ethyl and propyl in which the substituent is other than at the α-position. When R₃ and R₄ are phenylalkyl, they are preferably benzyl, the phenyl group being preferably unsubstituted. When R₃ and R₄ are cycloalkyl, they are preferably cyclohexyl; where the cyclohexyl is alkyl substituted, the substituents are preferably methyl. Where R₃ and R₄, together with the nitrogen atom to which they are attached, form a heterocyclic ring, this is preferably a pyrrolidine, piperidine or morpholine ring.

Preferably R₃ and R₄ are R₃ ' and R₄ ' where R₃ ' and R₄ ' are independently hydrogen, linear or branched C₁₋₆ alkyl linear hydroxy C₂₋₃ alkyl or, benzyl, or together with the N atom form a pyrrolidine, piperidine or morpholine ring. More preferred significances are R₃ " and R₄ ", which are independently hydrogen, linear or branched C₁₋₄ alkyl or, hydroxyethyl, or together with the N atom form a piperidine or morpholine ring. Particularly preferred significances of R₃ and R₄ are R₃ '" and R₄ '", where R₃ '" and R₄ '" are independently methyl or ethyl.

Groups R₅ and R₆ are also preferably identical, and the preferred significances given above for R₃ and R₄ apply equally to R₅ and R₆, except that R₅ and R₆ may not be hydrogen.

Where R₇ is alkyl it is preferably methyl or ethyl, more preferably methyl. R₇ is preferably R₇ ' where R₇ ' is methyl, ethyl or benzyl, particularly methyl.

Where X is a basic group NR₂ --Q--NR₃ R₄,

it is preferably X_(a) =--NR₂ '--Q--NR₃ 'R₄ ';

more preferably X_(b) =--NR₂ '--Q--NR₃ "R₄ ";

still more preferably X_(c) =--NR₂ '--(CH₂)₂₋₆ --NR₃ "R₄ ";

particularly X_(d) =--NR₂ '--(CH₂)₂ or ₃ --NR₃ '"R₄ '",

in which R₂ ' is preferably hydrogen.

Where X is a cationic group --NR₂ --Q--N.sup.⊕ R₅ R₆ R₇, then the preferred significances are as X_(a) -X_(d) above in which R₅ and R₆ are as R₃ and R₄, and R₇ is R₇ '. Particularly preferred is the group

X_(e) =--NR₂ '--(CH₂)₂ or ₃ --N.sup.⊕ (CH₃)₃.

Where X is a cationic group the corresponding anion is either a --SO₃.sup.⊖ group in the molecule or an external anion A.sup.⊖. The nature of A.sup.⊖ is not critical; it should however be non-chromophoric. Examples of suitable anions A.sup.⊖ are chloride, bromide, iodide, methanesulphonate, ethane sulphonate and hydrogen sulphate.

Where Y is an aliphatic amino group, it is preferably a monoalkylamino or dialkylamino group in which the alkyl groups have 1-4 carbon atoms, may be linear or branched, and may be unsubstituted or substituted by Cl, Br, phenyl or, preferably, hydroxy; or Y may be a C₅₋₆ cycloalkylamino group. Where Y is an aromatic amino group, it is preferably an anilino group, which may be unsubstituted or substituted in the phenyl ring by one or two substituents selected from halogen (preferably chlorine), C₁₋₄ alkyl, C₁₋₄ alkoxy, hydroxy and phenoxy.

Y is preferably Y_(a) where Y_(a) is Cl, OH, NH₂, mono(C₁₋₄)alkylamino, monohydroxy(C₂₋₄)alkylamino, di(C₁₋₂)alkylamino; bis[hydroxy(C₂₋₄)alkyl]amino or anilino. More preferably Y is Y_(b) where Y_(b) is Cl, OH or anilino.

As stated above, X_(I) signifies --CO--X or --SO₂ X, and X_(II) signifies ##STR12##

Preferred significances of the groups X_(I) are, independently,

X_(Ia) =--CO--X_(a) or --SO₂ --X_(a) ;

more preferably X_(Ib) =--CO--X_(b) or --SO₂ --X_(b) ;

still more preferably X_(Ic) =--CO--X_(c)

and particularly X_(Id) =--CO--X_(d), in which R₂ ' is preferably hydrogen.

This order of preferences applies also for cationic groups, in which however X_(I) is most preferably X_(Ie) where X_(Ie) is --CO--X_(e).

Preferred significances of the groups X_(II) are, independently.

    ______________________________________                                                  ##STR13##        where T is X.sub.a or Y.sub.a, in which Y.sub.a                                is more preferably Y.sub.b ;                         more preferably                                                                         ##STR14##                                                             still more preferably                                                                   ##STR15##                                                             and particularly                                                                        ##STR16##        in which R'.sub.1 and R'.sub.2  are preferably                                 hydrogen.                                            ______________________________________                                    

This order of preferences applies also for cationic groups, in which however X_(II) is most preferably X_(IIe), where X_(IIe) is ##STR17##

A group of preferred compounds of formula I are those of formula Ia ##STR18## in which the groups X_(Ia) are identical or different preferably identical,

R₈ is hydrogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, halogen, mono(C₁₋₄ alkyl)amino, di(C₁₋₄ alkyl)amino, --SO₂ NR₁ R₁ or --CONR₁ R₁, where R₁ is as defined above;

R₁₁ is hydrogen, halogen (preferably chlorine), C₁₋₄ alkyl, C₁₋₄ alkoxy, --NHCO--(C₁₋₄ alkyl), --NHCONH₂, --NHCO(CH₂)₁₋₃ N(C₁₋₄ alkyl)₂ or --NHCO(CH₂)₁₋₃ N.sup.⊕ (CH₃)₃ A.sup.⊖ where A.sup.⊖ is an anion;

R₁₂ is hydrogen, C₁₋₄ alkyl or C₁₋₄ alkoxy;

R₁₃ is hydrogen, NH₂, (C₁₋₄ alkyl)carbonylamino, benzoylamino whose phenyl ring may be substituted with up to 2 substituents selected from halogen, NO₂, NH₂, C₁₋₄ alkyl and C₁₋₄ alkoxy, or ##STR19## where R₁ and Y are as defined above and Y' has any significance of Y other than Cl;

and q is 0 or 1.

R₈ is preferably R₈ ' where R₈ ' is hydrogen, methyl, methoxy or chlorine, more preferably hydrogen.

In the group ##STR20## the phenylene linkages may be in the 1,3- or 1,4-positions; preferably the group has the structure ##STR21## R₁₁ is preferably R₁₁ ' where R₁₁ ' is hydrogen, methyl or methoxy.

R₁₂ is preferably R₁₂ ' where R₁₂ ' is hydrogen, methyl or methoxy.

R₁₃ is preferably R₁₃ ' where R₁₃ ' is hydrogen, NH₂, acetylamino or unsubstituted benzoylamino.

Preferred compounds of formula Ia are those in which

(1) X_(Ia) is X_(Ib), more preferably X_(Ic) and particularly X_(Id) or X_(Ie)

(2) R₈ is R₈ ', particularly hydrogen

(3) the group ##STR22## (4) R₁₃ is R₁₃ ', and (5) the X_(I) groups are in the 2,5- or 3,5-positions, counting from the carbon atom bearing the azo group.

Another group of preferred compounds of formula I are those of formula Ib ##STR23## in which the basic or cationic groups may be the same or different and are preferably located at the positions indicated in formulae IIIa, IIIb and/or IV above,

R₉ is hydrogen, halogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, phenoxy, NHCOR₁₄ '--SO₂ R₁₄, --SO₂ NR₁ R₁ or --CONR₁ R₁, where R₁ is as defined above, in which R₁₄ is C₁₋₄ alkyl or phenyl;

R₁₀ is hydrogen, halogen, C₁₋₄ alkyl or C₁₋₄ alkoxy;

r is 0 or 1;

and R₁₁, R₁₂, R₁₃, Z₁ ", Z₂, X_(a), m, n, p and q are as defined above.

Preferably R₉ is R₉ ' where R₉ ' is hydrogen, chlorine, methyl, methoxy, acetylamino, benzoylamio, --SO₂ NH₂ or --CONH₂. More preferably it is R₉ ", where R₉ " is hydrogen, chlorine, methyl, methoxy, acetylamino or benzoylamino, particularly hydrogen.

R₁₀ is preferably R₁₀ ' where R₁₀ ' is hydrogen, chlorine, methyl or methoxy, particularly hydrogen.

Preferably R₁₁, R₁₂ and R₁₃ are, independently, R₁₁ ', R₁₂ ' and R₁₃ '. The group R₁₃ is preferably in position 6. If r=0, then preferably a --Z₁ "--X_(a) or --Z₂ --(X_(a))₂ group occupies position 6. Preferably m=1, and in this case the sulpho group is in position 3 or 4, preferably in position 3.

Preferred compounds of formula Ib are those in which, independently,

(1) R₉ is R₉ ', more preferably R₉ ", particularly hydrogen,

(2) R₁₀ is R₁₀ ', particularly hydrogen,

(3) the group ##STR24## (4) R₁₃ is R₁₃ ' in position 6, or (5) r=0, and a basic or cationic group is in position 6,

(6) the groups X_(a) are preferably X_(b), more preferably X_(c), particularly X_(d) or X_(e),

(7) m=1 and the sulpho group is in position 3.

More preferred compounds of formula Ib are those of formula Ic ##STR25## in which X_(IIb) and R₉ ' are as defined above.

Particularly preferred compounds of formula Ic are those in which, independently,

(1) R₉ ' is R₉ ", particularly hydrogen,

(2) X_(IIb) is X_(IIc), more preferably X_(IId) or X_(IIe),

R₁₁ ' and R₁₂ ' are hydrogen.

A further group of more preferred compounds of formula Ib are those of formula Id ##STR26## particularly those in which, independently, (1) R₉ ' is R₉ " and R₁₀ ' is hydrogen,

(2) X_(IIb) is X_(IIc), more preferably X_(IId) or X_(IIe),

(3) R₁₁ ' and R₁₂ ' are hydrogen,

(4) q=1.

Other groups of preferred compounds of formula I are those of formula Ie ##STR27## wherein the groups X_(Ia) are preferably identical, and Z₃ is a divalent N-containing bridging group.

The variables in the two parts of the molecule connected by Z₃ may be the same or different but are preferably the same.

Z₃ is preferably Z_(3a) where Z_(3a) is --NH--; --NHCONH--; ##STR28## in which Y is as defined above and is preferably Y_(c) where Y_(c) is Cl, NH₂ or --NH--phenyl; ##STR29## containing a 1,3- or 1,4-phenylene group; --NHCOCH₂ CH₂ CONH--; or --NHCOCH═CHCONH--. More preferably it is Z_(3b) where Z_(3b) is --NHCONH--; ##STR30## --NHCOCH₂ CH₂ CONH-- or --NHCOCH═CHCONH--; particularly preferred is Z_(3c), i.e. --NHCONH--, ##STR31##

Preferred compounds of formula Ie are those in which, independently,

(1) R₈ is R₈ ', particularly hydrogen,

(2) X_(Ia) is X_(Ib), more preferably X_(Ic) and particularly X_(Id) or X_(Ie),

(3) Z₃ is Z_(3a), preferably Z_(3b), particularly Z_(3c),

(4) Groups X_(Ia) are in the 2,5- or 3,5-positions with respect to the carbon atom bearing the azo group.

A further group of preferred compounds of formula I are those of formula If ##STR32## in which R₉ ', X_(IIb) and Z₃ are as defined above, and X_(IIb) preferably occupies the positions shown in formulae IIIa and b. The variables in the two parts of the molecule joined by bridging group Z₃ may be the same or different but are preferably the same.

Preferred compounds of formula If are those in which, independently,

(1) R₉ ' is R₉ ", particularly hydrogen,

(2) X_(IIb) is X_(IIc), particularly X_(IId) or X_(IIe),

(3) Z₃ is Z_(3a), more preferably Z_(3b), particularly Z_(3c),

(4) the sulpho group is in position 3, the bridging group Z₃ is in position 6 and both parts of the molecule joined by Z₃ are identical.

A still further preferred group of compounds of formula I have formula Ig ##STR33## in which the bridging group Z₄ is 1,3- or 1,4-phenylene or a group of the formula ##STR34## where R₁₅ is hydrogen, chlorine, methyl or methoxy, particularly hydrogen,

and Z₅ is a direct bond, --(CH₂)_(t) --, --O--, --O(CH₂)_(t) O--, --SO₂ --, --NHCO--, --NHCONH--, --NHCO(CH₂)_(t) CONH-- or --CONH(CH₂)_(t) NHCO--, where t is 2 or 3, preferably 2.

Z₄ is preferably Z_(4a) where Z_(4a) is 3,3'- or 4,4'-phenylene. The two parts of the molecule joined by Z₄ may be identical or different but are preferably identical. ##STR35##

Preferred compounds of formula Ig are those in which

(1) X_(IIb) is X_(IIc), particularly X_(IId) or X_(IIe),

(2) Z₄ is Z_(4a), and

(3) the sulpho group is in position 3, the group X_(IIb) in position 6, and the two parts of the molecule are identical.

The invention also provides a process for the preparation of compounds of formula I comprising the step of coupling to a corresponding terminal coupling component a corresponding diazotised amine or monoazoamine, the necessary n (-Z₁ -X) and/or ##STR36## groups being already present in the coupling component and/or the diazo component.

Compounds of formula I containing X_(II) groups, for example compounds of formula Ib, Ic, Id, If or Ig, may also be prepared by reacting a compound of formula V ##STR37## in which Hal is halogen, particularly chlorine, in any desired order with n+2p moles of a diamine of formula VIa and/or formula VIb

    HNR.sub.2 -Q-NR.sub.3 R.sub.4                              VIa

    HNR.sub.2 -Q-N.sup.⊕ R.sub.5 R.sub.6 R.sub.7           VIb

and optionally with n moles of a compound HY'.

In all the above definitions, the term "halogen" signifies fluorine, chlorine or bromine.

The processes, of which the former is preferred, are carried out in conventional manner. Thus the coupling reaction may be carried out in weakly acid or weakly alkaline aqueous media, and the products may be isolated and purified in known manner.

The compounds of formula I may be transformed into water-soluble salt forms by treating the basic compounds with at least a stoichiometric quantity of an organic or inorganic acid. In the compounds of formula I, free basic (i.e. non-protonated) X groups may also be treated with alkylating agents containing the group R₇ to give quaternary ammonium-containing cationic X groups.

The starting diazo and coupling components are either known or can be obtained from available starting materials by known or analogous processes. Thus, for example, the diazo components containing groups X_(I) for the compounds of formula Ia or Ie may be prepared by reaction of the corresponding nitrophenylcarboxylic acid chloride or nitrophenyl sulphonylchloride with stoichiometric amounts of one or more diamines of formula VIa and/or VIb and finally reducing the nitro group to an amino group.

The diazo components containing group X_(II) for the compounds of formulae Ib, Ic and If may for example be prepared by reaction of cyanuric halide with an optionally substituted nitroaniline, a diamine of formula VIa and/or VIb and optionally a compound HY' in any desired order, and finally reducing the nitro group.

Similarly, the group X_(II) -containing coupling components for compounds of formula Ib, Id or Ig may be obtained by condensing a cyanuric halide with the corresponding amino-containing coupling component, diamine of formula VIa and/or VIb and optionally compound HY' in any desired order.

Compounds of formula I in the form of their water-soluble acid salts are dyestuffs useful for dyeing or printing substrates consisting of or containing cellulosic fibres, for example cotton, or preferably for the dyeing or printing of paper. They may also be used for dyeing or printing leather, particularly vegetable-tanned low-affinity leather.

Cotton may for example be dyed by an exhaust dyeing process at room temperature to the boil or printed with printing pastes of conventional type. Sized or unsized paper may be printed or dyed in the mass during the manufacturing process or by the dipping process. Leather may be dyed in conventional manner.

Compounds of formula I may also be used in the form of liquid or solid dye compositions. They may be produced in the form of stable liquid, preferably aqueous, compositions by known methods, preferably by solution in a suitable solvent, optionally in the presence of an auxiliary, for example a stabiliser. Such compositions may for example be prepared as disclosed in French Pat. No. 1,572,030. A suitable liquid composition is for example the following (parts are by weight):

100 parts compound of formula I as acid salt

1-100, preferably 1-10, parts inorganic salt

1-100 parts of an organic acid, e.g. formic, acetic, lactic or citric acid

100-800 parts water

0-500 parts of a solubilising agent, for example glycols such as diethylene, triethylene or hexylene glycol; glycol ethers such as methyl cellosolve, methyl carbitol, butylpolyglycol; urea; formamide; dimethylformamide, etc.

The compounds of formula I may also be prepared in solid, preferably granular, form, preferably by granulating as described in French Pat. No. 1,581,900. A suitable solid composition is for example the following (parts are by weight):

100 parts compound of formula I as acid salt

1-100, preferably 1-10, parts inorganic salt

0-800 parts of a filler, preferably a nonionic material such as dextrin, sugar, glucose or urea.

The solid compositions may contain up to 10% residual moisture.

The dyestuffs of formula I, in the form of their acid salts, have good solubility properties, particularly good solubility in cold water. When used in paper-making, they colour the waste water only slightly or not at all, which is desirable for ecological reasons. They do not give mottling of the dyed paper and are insensitive to pH over wide ranges. The resulting dyeings on paper are brilliant and are characterised by good light-fastness; after long illumination the shades change tone-in-tone. The dyed paper is fast not only to water but also to milk, fruit juices and sweetened mineral water; because of the good alcohol fastness of the dyes (particularly those of formula Ie, If and Ig), it is also resistant to alcoholic drinks.

The dyes exhibit high substantivity, that is they exhaust practically quantitatively on the substrate. They may be added to the paper mass directly in the form of a dry powder or granulate, without first making up a solution, without loss of brilliance or yield. The dyes according to the invention may also be used in soft water without loss of yield.

Fibrous materials containing wood pulp are dyed with the dyestuffs according to the invention in as good and level quality as with purely cationic dyes.

The dyed paper is both oxidatively and reductively bleachable, which is important for the recycling of waste paper.

The following Examples, in which solid materials are given as parts by weight and liquids as parts by volume, all percentages are weight percentages and temperatures are in degrees Centigrade, illustrate the invention.

PREPARATION OF STARTING MATERIALS EXAMPLE (A)

106 Parts 5-nitroisophthalic acid are stirred into 300 parts chlorobenzene containing 0.5 part triethylamine and warmed to 80° C.; finally 80 parts thionyl chloride are slowly added dropwise. After stirring 3 hours at 80°, the temperature is raised slowly to 120°. When all is dissolved, the solution is cooled to 90° and a mixture of 137 parts 3-dimethylaminopropylamine and 60 parts chlorobenzene is added dropwise; finally 53 parts sodium carbonate are added. The resulting suspension is stirred 2 hours at 100°, cooled and treated with 100 parts water. The mixture is acidified to pH 5 with 30% hydrochloric acid and the chlorobenzene removed by steam distillation.

The residual aqueous solution is made alkaline, causing the nitro product to separate as an oil, which is taken up in ethyl acetate, washed with brine, dried and evaporated to give a brown oil. The oil is dissolved in 200 parts water and 120 parts 30% hydrochloric acid, and this solution is added dropwise to a hot suspension of 100 parts iron turnings, 100 parts water and 10 parts 30% HCl. After 2 hours at 95°-98° the reduction is complete. Sodium carbonate is added to make the mixture alkaline to brilliant yellow indicator, and the product is filtered hot. The filtrate (˜520 parts by volume) contains 110 parts of the compound of the formula ##STR38##

EXAMPLE (B)

If example (a) is repeated using nitroterephthalic acid, the product is the compound of the formula ##STR39##

EXAMPLE (C)

92 Parts cyanuric chloride are dissolved in 750 parts acetone and cooled to 0°-5°. 69 Parts 3-nitroaniline are added, then 130 parts of a 4 N sodium carbonate solution are added dropwise over an hour. The mixture is stirred for an hour, then 600 parts of ice water are added. The resulting suspension is filtered and the moist residue is added slowly in small portions to 250 parts 3-dimethylaminopropylamine. The temperature of the mixture rises to 60°-70°, giving a syrupy solution which is stirred for 1 hour at 90°-100° and then diluted to 1000 parts by volume by addition of ice. The aqueous phase is separated off, and the resinous residue is stirred with 200 parts water and 90 parts 30% HCl, giving an aqueous suspension with a pH of 5.

In a second vessel 300 parts of water, 70 parts iron turnings and 20 parts 30% HCl are stirred together for 1 hour. The weakly acid suspension prepared as above is added, and the temperature is held for 2 hours at 95°-98°. The product is made alkaline to brilliant yellow by adding sodium carbonate and filtered hot. The yellow-brown filtrate (˜950 parts by volume) contains 155 parts of the compound of the formula ##STR40##

In place of the 3-nitroaniline, the following nitro compounds may also be used to produce corresponding products: 4-nitroaniline, 2-chloro- or 2-bromo-4-nitroaniline, 2-methyl-4-nitroaniline, 2-methoxy-4-nitroaniline, 2-methyl-3-nitroaniline, 4-chloro-3-nitroaniline, 4-methyl-3-nitroaniline, 4-methoxy-3-nitroaniline, 2-methyl-5-nitroaniline, 2-methoxy-5-nitroaniline and 5-chloro-2-methoxy-3-nitroaniline.

EXAMPLE (d)

A mixture of water and ice (125 parts each) is stirred with 92 parts cyanuric chloride to give a fine dispersion. 130 Parts 3-diethylaminopropylamine is added dropwise over 3 hours, at a rate such that the temperature does not exceed 5°. The product is stirred for 1 hour at 45°-50° and treated with 100 parts 30% caustic soda solution, causing the product to separate as a white mass which is suction filtered and washed with water. After drying in vacuum at 60°, 150 parts of 2,4-diamino-N,N'-bis-(3-diethylaminopropyl)-6-chloro-1,3,5-triazine are obtained.

This product is dissolved in 600 parts water and 106 parts 30% HCl, and 95 parts 6-amino-1-naphthol-3-sulphonic acid are added followed by 100 parts sodium acetate. The mixture is heated to 90°-95°, the pH sinking from 4.5 to 3.7. After 3 hours the reaction is complete, and on cooling a clear brown solution, containing 210 parts of the compound of the formula ##STR41## is obtained.

The use of alternative diamines in the process of examples a-d gives the corresponding alternative diazo components or coupling components as shown in Table 1.

                                      TABLE 1                                      __________________________________________________________________________                                             reacted with the con-                                                          densation product                                                                         reacted with cyanuric                           reacted with 5-nitro-                                                                    reacted with nitro-                                                                      cyanuric chloride                                                                         chloride and 6-amino-                           isophthalic acid and                                                                     terephthalic acid                                                                        3-nitroaniline and                                                                        1-naphthol-3-sulphonic                                                         8                                               reduced gives diazo                                                                      and reduced gives                                                                        reduced gives                                                                             acid gives the                                                                 coupling                    Diamine             component:                                                                               diazo component:                                                                         the diazo component:                                                                      component:                  __________________________________________________________________________     H.sub.2 N(CH.sub.2).sub.3N(CH.sub.3).sub.2                                                         D.sub.1a (Example a)                                                                     D.sub.1b (Example b)                                                                     D.sub.1c (Example                                                                         K.sub.2d                    H.sub.2 N(CH.sub.2).sub.3N(C.sub.2 H.sub.5).sub.2                                                  D.sub.2a  D.sub.2b  D.sub.2c   K.sub.1d (Example d)        H.sub.2 N(CH.sub.2).sub.2N(CH.sub.3).sub.2                                                         D.sub.3a  D.sub.3b  D.sub.3c   K.sub.3d                    H.sub.2 N(CH.sub.2).sub.2N(C.sub.2 H.sub.5).sub.2                                                  D.sub.4a  D.sub.4b  D.sub.4c   K.sub.4d                     ##STR42##          D.sub.5a  D.sub.5b  D.sub.5c   K.sub.5d                     ##STR43##          D.sub.6a  D.sub.6b  D.sub.6c   K.sub.6d                     ##STR44##          D.sub.7a  D.sub.7b  D.sub.7c   K.sub.7d                     ##STR45##          D.sub.8a  D.sub.8b  D.sub.8c   K.sub.8d                     ##STR46##          D.sub.9a  D.sub.9b  D.sub.9c   K.sub.9d                     ##STR47##          D.sub.10a D.sub.10b D.sub.10c  K.sub.10d                    ##STR48##          D.sub.11a D.sub.11b D.sub.11c  K.sub.11d                   H.sub.2 N(CH.sub.2).sub.5N(C.sub.2 H.sub.5).sub.2                                                  D.sub.12a D.sub.12b D.sub.12c  K.sub.12d                   H.sub.2 N(CH.sub.2).sub.6N(CH.sub.3).sub. 2                                                        D.sub.13a D.sub.13b D.sub.13c  K.sub.13d                   H.sub.2 N(CH.sub.2).sub.3N(CH.sub.2 CH.sub.2 OH).sub.2                                             D.sub.14a D.sub.14b D.sub.14c  K.sub.14d                   __________________________________________________________________________      Diazo components as listed in column 4 but prepared using 4niroaniline ar      designated D.sub.1c' -D.sub.14c'  and those prepared using                     4methyl-3-nitroaniline are designated D.sub.1c" -D.sub.14c".             

EXAMPLE 1

24 Parts by volume of the solution prepared as in Example (c) are treated with 20 parts ice and 3 parts 30% HCl and diazotised with 10 parts 1 N sodium nitrite solution at 0°-5°. The diazonium salt solution is added dropwise to a mixture of 3 parts 6-acetylamino-1-naphthol-3-sulphonic acid (K₁) and 100 parts water, maintaining the pH at 7-8 by addition of sodium carbonate solution. An orange dyestuff suspension is obtained. When no more diazonium salt can be detected, the suspension is treated with zinc chloride until the run-off of a spot test has become almost colourless. The dyestuff is filtered off and dried at 80° in a vacuum. The product of the formula ##STR49## is obtained in the form of a powder which is easily soluble in weakly acid to acid aqueous media and dyes paper in red-orange tones. The dyed paper has good light- and wet-fastness.

EXAMPLE 2

If instead of 24 parts of the solution of Example (c), 18 parts of the solution obtained in Example (a) is used in Example 1, a dyestuff having the formula ##STR50## is obtained in the form of a powder which is soluble in acidic aqueous media and gives on paper yellow-orange dyeings having good light- and wet-fastness.

EXAMPLES 3-27

Following the procedure of Example 1 and using the coupling and diazo components listed in Table 2 below, further monoazo dyestuffs can be obtained which dye paper in the colours indicated, with good light- and wet-fastness.

    ______________________________________                                         Abbreviations used for colours:                                                ______________________________________                                         yo = yellow-orange  bo = brown-orange                                          r = red             bor = bordeaux red                                         brv = brilliant red-violet                                                                         o = orange                                                 or = orange-red     blr = bluish-red                                           br = brown-red      v = violet                                                 ro = red-orange     sr = scarlet red                                           bbr = brilliant bluish-red                                                                         rv = red-violet                                            ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                         Example                  Diazo                                                 No.    Coupling Component                                                                               Component  Colour                                     ______________________________________                                         3      6-benzoylamino-1-naphthol-                                                                       D.sub.1c   ro                                                3-sulfonic acid (K.sub.2)                                               4      1-naphthol-3-sulfonic                                                                            "          ro                                                acid (K.sub.3)                                                          5      1-naphthol-4-sulfonic                                                                            "          ro                                                acid (K.sub.4)                                                          6        K.sub.1         D.sub.1c'  blr                                        7        K.sub.2         D.sub.1c'  blr                                        8        K.sub.3         "          blr                                        9        K.sub.4         "          blr                                        10       K.sub.1         D.sub.1c"  r                                          11       K.sub.2         "          r                                          12       K.sub.3         "          r                                          13       K.sub.4         "          r                                          14       K.sub.1         D.sub.2c   ro                                         15       K.sub.2         "          ro                                         16       K.sub.3         "          ro                                         17       K.sub.4         "          ro                                         18       K.sub.1         D.sub.2c'  blr                                        19       K.sub.2         "          blr                                        20       K.sub.3         "          blr                                        21       K.sub.4         "          blr                                        22       K.sub.1         D.sub.1b   ro                                         23a      K.sub.2         D.sub.1a   yo                                         23b      K.sub.2         D.sub.1b   ro                                         24a      K.sub.3         D.sub.1a   yo                                         24b      K.sub.3         D.sub.1b   ro                                         25a      K.sub.4         D.sub.1a   yo                                         25b      K.sub.4         D.sub.1b   ro                                         26       K.sub.1         D.sub.2a   yo                                         27       K.sub.3         D.sub.2b   yo                                         ______________________________________                                    

Similarly, coupling components K₁ -K₄ can be reacted with any of the diazo components listed in Table 1 to give dyestuffs which give dyeings on paper with good light- and wet-fastness.

EXAMPLE 28

67 Parts by volume of the solution prepared in Example (a) are treated with 50 parts ice and 10 parts 30% HCl and diazotised at 0°-5° with 10.5 parts 4 N sodium nitrite solution. To the diazonium salt solution is added 50 parts ice and enough sodium acetate to hold the pH at 3.5. Then, 4.7 parts 3-methylaniline are added and the mixture stirred at pH 3-3.5 until no more diazonium salt is detectable. The dyestuff solution is made alkaline with caustic soda, and the dyestuff which comes out of solution is separated and dissolved in 300 parts water and 20 parts 30% HCl.

The intermediate product is diazotised with 9 parts of 4 N sodium nitrite solution at room temperature, and the diazo solution is added dropwise to a suspension of 13.6 parts 6-benzoylamino-1-naphthol-3-sulphonic acid in 500 parts of water, keeping the pH at 7-7.5. As soon as no more diazonium salt is detectable, the blue-red dyestuff solution is treated with zinc chloride to give a filterable suspension. By filtration and vacuum drying at 60° is obtained in powder form the dyestuff of the formula ##STR51## ps which is soluble in acidic aqueous media and dyes paper in bordeaux red shades; the dyeings have good light- and wet-fastness.

EXAMPLE 29

When 90 parts of the solution of Example (c) are used in place of the 67 parts of the solution of Example (a) the dyestuff of the formula ##STR52## is obtained, which dyes paper in blue-red shades, with good light- and wet-fastness properties.

EXAMPLES 30-47

Following the procedure of Example 28 and using the diazo, middle and terminal coupling components given in Table 3 below, disazo dyestuffs are obtained which dye paper in fast shades of the colours indicated.

                  TABLE 3                                                          ______________________________________                                                                       Terminal                                         Ex-                           Coupling                                         ample Diazo                   Component                                        No.   Component Middle Component                                                                             (see Table 2)                                                                           Colour                                  ______________________________________                                         30    D.sub.1c  aniline       K.sub.4  br                                      31    "         2-methoxyaniline                                                                             "        rv                                      32    "         "             K.sub.3  brv                                     33    D.sub.2c' 3-methylaniline                                                                              "        v                                       34    "         aniline       K.sub.1  v                                       35    D.sub.2c  2-methoxyaniline                                                                             "        br                                      36    D.sub.1a  3-methylaniline                                                                              K.sub.3  bbr                                     37    D.sub.2a  "             "        bbr                                      38a  D.sub.1a  "             K.sub.1  r                                        38b  "         "             K.sub.4  br                                      39    D.sub.2a  "             K.sub.1  r                                       40    D.sub.1b  "             K.sub.1  r                                       41    D.sub.2a  aniline       "        bo                                      42    D.sub.2b  "             "        r                                       43    D.sub.1a  "             "        bo                                      44    D.sub.1b  aniline       K.sub.1  bo                                      45    D.sub.3a  "             "        bo                                      46    D.sub.1a  2-methoxyaniline                                                                             "        rv                                      47    D.sub.2a  "             "        rv                                      ______________________________________                                    

Similarly, any other combinations of the diazo components listed in Table 1 with coupling components K₁ -K₄ and the middle components listed in Table 3 give disazo dyestuffs which dye paper in brown-red to red-violet or bordeaux red to brilliant blue-red shades, the dyeings having good fastness properties.

EXAMPLE 48

3.15 Parts of the compound of the formula ##STR53## in which Z₃ is --NHCONH-- and the sulphonic acid groups are in the 3,3'-positions are dispersed in 200 parts water. The solution obtained in Example (c) (35.5 parts) is diazotised and added dropwise over 30 minutes, keeping the pH at 7-8 by addition of sodium carbonate. After 1 hour the product is filtered and dried in vacuum at 60°, giving the dyestuff of the formula ##STR54## which is soluble in acidic aqueous media and gives orange dyeings on paper having particularly good wet-fastness and very good fastness to alcohol.

EXAMPLE 49

If, instead of 35.5 parts of the product of Example (c), 21.1 parts of the product of Example (a) is taken, a dyestuff is obtained having the formula ##STR55## which is soluble in acidic aqueous media and gives orange dyeings on paper having good wet fastness, in particular good fastness to alcohol.

EXAMPLES 50-78

In manner analogous to Example 48, corresponding compounds may be prepared using a diazo component given in column 2 of Table 4 below and a coupling component of the formula given in Example 48, in which the bridging group Z₃ and the position of the sulphonic acid groups are given in columns 3 and 4 of the Table. The colour of the dyeings obtained on paper is indicated in column 5; such dyeings show good wet- and alcohol-fastness.

                                      TABLE 4                                      __________________________________________________________________________     Example                                                                             Diazo                  Position of                                        No.  Component                                                                              Z.sub.3        Sulpho Groups                                                                            Colour                                   __________________________________________________________________________     50   D.sub.1c                                                                               HNCOCHCHCONH   3,3'      ro                                       51   "                                                                                       ##STR56##     "         o                                        52   "                                                                                       ##STR57##     "         o                                        53   "                                                                                       ##STR58##     "         bo                                       54   "       HNCOC.sub.2 H.sub.4 CONH                                                                      "         o                                        55   "       NH             "         blr                                      56   D.sub.2c                                                                               NHCONH         "         o                                        57   "       "              4,4'      o                                        58   "                                                                                       ##STR59##     "         bo                                       59   D.sub.1c                                                                               "              3,3'      bor                                      60   "                                                                                       ##STR60##     "         bor                                      61   D.sub.1c                                                                               HNCOCHCHCONH   3,3'      rv                                       62   D.sub.2c                                                                               HNCONH         "         bor                                      63   "                                                                                       ##STR61##     "         br                                       64   "       HNCOC.sub.2 H.sub.4 CONH                                                                      "         blr                                      65   D.sub.4c                                                                               HNCOC.sub.2 H.sub.4 CONH                                                                      3,3'      o                                        66   "       HNCONH         "         o                                        67   D.sub.1b                                                                               "              "         o                                        68   D.sub.2a                                                                               "              "         o                                        69   D.sub.2a                                                                               "              4,4'      o                                        70   D.sub.3a                                                                               "              3,3'      o                                        71a  D.sub.1a                         o                                                     HNCOCHCHCONH   "                                                  71b  D.sub.2a                         o                                        72a 72b                                                                             D.sub.1a D.sub.2a                                                                       ##STR62##     "         oo                                       73a 73b                                                                             D.sub.1a D.sub.2a                                                                       ##STR63##     3,3'      ro ro                                    74a 74b                                                                             D.sub.1a D.sub.2a                                                                       ##STR64##     "         ro ro                                    75a  D.sub.1a                         ro                                                    "              4,4'                                               75b  D.sub.2a                         ro                                       76a  D.sub.1a                         bbr                                                   NH             3,3'                                               76b  D.sub.1b                         bbr                                      77a  D.sub.1a                         o                                                     HNCOC.sub.2 H.sub.4 CONH                                                                      "                                                  77b  D.sub.1b                         o                                        78a  D.sub.2a                         o                                                     "              "                                                  78b  D.sub.2b                         o                                        __________________________________________________________________________

Analogous dyes with similar properties may be made using any of the above-indicated coupling components with any of the diazo components listed in Table 1.

EXAMPLE 79

6.2 Parts of 4-methoxyaniline are dissolved in 100 parts water and 25 parts 30% HCl and cooled to 0°-5°. To the solution is added dropwise 50 parts of 1 N sodium nitrite solution.

In a second reaction vessel is placed 140 parts by volume of the solution prepared as in Example (d), and the above diazo solution is added dropwise at pH 6-6.5. The mixture is stirred overnight, then treated with 90 parts sodium chloride and 15 parts zinc chloride. The dyestuff is filtered and vacuum dried at 60° to give a powder of the formula ##STR65## which is soluble in acidic aqueous media and dyes paper in scarlet red shades, the dyeings having good light- and wet-fastness.

EXAMPLES 80-97

In manner analogous to Example 79, analogous monoazo compounds may be prepared using the diazo components and coupling components given in Table 5 below. The resulting compounds dye paper in the indicated shades, the dyeings having good light- and wet-fastness.

                  TABLE 5                                                          ______________________________________                                         Example                  Coupling                                              No.     Diazo Component  Component   Colour                                    ______________________________________                                         80      4-methoxyaniline K.sub.2d    sr                                        81a     2-methoxyaniline K.sub.1d    ro                                        81b        "             K.sub.2d    ro                                        82a     1-amino-4-benzoylamino-                                                                         K.sub.1d    blr                                               benzene                                                                82b     1-amino-4-benzoylamino-                                                                         K.sub.2d    blr                                               benzene                                                                83a     1-amino-4-acetylamino-                                                                          K.sub.1d    blr                                               benzene                                                                83b     1-amino-4-acetylamino-                                                                          K.sub.2d    blr                                               benzene                                                                84a     4-aminodiphenylether                                                                            K.sub.1d    ro                                        84b        "             K.sub.2d    ro                                        85a     2,5-dimethoxyaniline                                                                            K.sub.1d    blr                                       85b        "             K.sub.2d    blr                                       86         "             K.sub.3d    blr                                       87a     2,5-dimethylaniline                                                                             K.sub.1d    o                                         87b        "             K.sub.2d    o                                         88a     2-methoxy-5-methylaniline                                                                       K.sub.1d    r                                         88b        "             K.sub.2d    r                                         89         "             K.sub.4d    r                                         90a     aniline          K.sub.1d    yo                                        90b        "             K.sub.2d    yo                                        91         "             K.sub.4d    yo                                        92a     3-chloro-4-methylaniline                                                                        K.sub.1d    o                                         92b        "             K.sub.2d    o                                         93      2-aminonaphthalene-                                                                             K.sub.1d    ro                                                sulfonamide                                                            94      4-methylaniline  K.sub.1d    o                                         95a     4-aminobenzanilide                                                                              K.sub.1d    yo                                        95b         "            K.sub.2d    yo                                        96      2-(4'-aminophenyl)-6-                                                                           K.sub.2d    ro                                                methylbenzathiazol                                                     97      2-aminodibenzofuran                                                                             K.sub.2d    o                                         ______________________________________                                    

Analogous compounds may be prepared by the use of the above diazo components with the other coupling components listed in Table 1.

EXAMPLE 98

9.9 Parts 4-aminoazobenzene are stirred overnight with 100 parts water and 25 parts 30% HCl and diazotised by adding dropwise 50 parts of 1 N sodium nitrite solution. In a second reaction vessel is placed 140 parts by volume of a solution containing 28 parts of the compound described in Example (d), together with 30 parts sodium acetate. The diazo solution is added dropwise at pH 3-4, and the mixture is stirred overnight, then treated with 50 parts 30% caustic soda to bring the pH to 8-9. After stirring for 1 hour, the precipitated dyestuff is filtered and dried to give a powder of the formula ##STR66## which is soluble in acidic aqueous media and gives bluish-red dyeings on paper which exhibit good light- and wet-fastness.

EXAMPLES 99-111

In manner analogous to Example 98 and using the diazo components, middle components and terminal coupling components given in Table 6 below, corresponding dyestuffs are obtained which dye paper in the indicated shades, the dyeings having good light- and wet-fastness.

                  TABLE 6                                                          ______________________________________                                                                        Terminal                                        Ex.  Diazo        Middle       Coupling                                        No.  Component    Component    Component                                                                              Colour                                  ______________________________________                                          99  aniline      aniline      K.sub.2d                                                                               blr                                     100a   "            "          K.sub.3d                                                                               blr                                     100b   "            "          K.sub.4d                                                                               blr                                     101a   "          2-methoxyaniline                                                                            K.sub.1d                                                                               rv                                      101b   "            "          K.sub.2d                                                                               rv                                      102a   "          3-methylaniline                                                                             K.sub.1d                                                                               bor                                     102b   "            "          K.sub.2d                                                                               bor                                     103a 2,5-dimethoxy-                                                                              aniline      K.sub.1d                                                                               blr                                          aniline                                                                   103b 2,5-dimethoxy-                                                                                "          K.sub.2d                                                                               blr                                          aniline                                                                   104a 4-methylaniline                                                                               "          K.sub.1d                                                                               blr                                     104b   "            "          K.sub.2d                                                                               blr                                     105a   "            "          K.sub.3d                                                                               blr                                     105b   "            "          K.sub.4d                                                                               blr                                     106a 4-methylaniline                                                                             2-methoxyaniline                                                                            K.sub.1d                                                                               rv                                      106b   "            "          K.sub.2d                                                                               rv                                      107a 1-amino-4-acetyl-                                                                           aniline      K.sub.1d                                                                               blr                                          aminobenzene                                                              107b 1-amino-4-acetyl-                                                                             "          K.sub.2d                                                                               blr                                          aminobenzene                                                              108a 3-chloro-4-methyl-                                                                          3-methylaniline                                                                             K.sub.1d                                                                               br                                           aniline                                                                   108b 3-chloro-4-methyl-                                                                            "          K.sub.2d                                                                               br                                           aniline                                                                   109a 3-aminobenzene-                                                                             2-methoxyaniline                                                                            K.sub.1d                                                                               v                                            sulfonamide                                                               109b 3-aminobenzene-                                                                               "          K.sub.2d                                                                               v                                            sulfonamide                                                               110a 3-aminobenzamide                                                                            aniline      K.sub.1d                                                                               blr                                     110b   "            "          K.sub.2d                                                                               blr                                     111a 3-aminophenyl-                                                                                "          K.sub.1d                                                                               blr                                          methylsulfone                                                             111b 3-aminophenyl-                                                                                "          K.sub.2d                                                                               blr                                          methylsulfone                                                             ______________________________________                                    

Analogous compounds may be prepared using the diazo and middle components listed in Table 6 with the remaining coupling components listed in Table 1.

EXAMPLE 112

A diazo solution is prepared by adding 27 parts of a 4 N sodium nitrite solution dropwise to a suspension of 15 parts 3-aminoacetanilide in 100 parts water and 25 parts 30% HCl at 0°-5°. This diazo solution is poured into a mixture of 60 parts of the solution prepared in Example (d), 200 parts water and 100 parts ice, holding the pH at 3-3.5 by dropwise addition of 70 parts 4 N sodium carbonate solution. After 2 hours 45 parts 65% sulphuric acid are added and the mixture is stirred for 3 hours at 85°, by which time the cleavage of the acetyl group is practically complete. The solution is cooled to room temperature and treated with 15 parts zinc chloride and, after 10 minutes, 60 parts common salt.

The resulting dyestuff is filtered off, stirred in 300 parts water and 20 parts 30% HCl and diazotised with 25 parts of 4 N sodium nitrite solution. The diazo solution is then added to 60 parts of the solution prepared as in Example (d), 300 parts water and 100 parts ice, at a pH of 4-4.5. When coupling is complete, the solution is made alkaline with caustic soda, and the precipitated dyestuff filtered and dried. The resulting compound has the formula ##STR67## has good solubility in acidic aqueous media and dyes paper in organic shades having excellent wet- and alcohol-fastness.

EXAMPLE 113

10.6 Parts 4,4'-diaminodibenzyl are dissolved in 300 parts water and 25 parts 30% HCl, cooled to 0°-5° and tetraazotised with 27 parts 4 N sodium nitrite. The mixture is treated with aminosulphonic acid to destroy residual nitrous acid, and the tetraazo solution is poured into a mixture of 60 parts of the product of Example (d), 700 parts water and 75 parts salt, keeping the pH at 4-5 by addition of ˜50 parts sodium acetate. After coupling the dyestuff was precipitated with caustic soda, filtered and dried. The resulting dyestuff, of the formula ##STR68## has good solubility in acidic aqueous media, and gives on paper red-orange dyeings having extremely good wet- and alcohol-fastness.

EXAMPLES 114-128

In manner analogous to Example 113, corresponding dyestuffs are produced from the diamines and coupling components listed in Table 7 below. The resulting dyestuffs give dyeings on paper of the shades indicated, having good wet fastness and particularly good fastness to alcohol.

                                      TABLE 7                                      __________________________________________________________________________     Example                                                                        No.  Tetraazo Component      Coupling Component                                                                        Colour                                 __________________________________________________________________________     114a                                                                                 ##STR69##              K.sub.1d   ro                                     114b    "                    K.sub.2d   ro                                     115a                                                                                 ##STR70##              "          ro                                     115b    "                    "          ro                                     116a                                                                                 ##STR71##              "          yo                                     116b    "                    "          yo                                     117                                                                                  ##STR72##              K.sub.2d   ro                                     118     "                    K.sub.4d   ro                                     119a                                                                                 ##STR73##              K.sub.1d   ro                                     119b    "                    K.sub.2d   ro                                     120a                                                                                 ##STR74##              K.sub.1d   yo                                     120b    "                    K.sub.2d   yo                                     121a                                                                                 ##STR75##              K.sub.1d   blr                                    121b    "                    K.sub.2d   blr                                    122a                                                                                 ##STR76##              K.sub.1d   yo                                     122b    "                    K.sub.2d   yo                                     123a                                                                                 ##STR77##              K.sub.1d   o                                      123b    "                    K.sub. 2d  o                                      124a                                                                                 ##STR78##              K.sub.1d   o                                      124b    "                    K.sub.2d   o                                      125a                                                                                 ##STR79##              K.sub.1d   r                                      125b    "                    K.sub.2d   r                                      126a                                                                                 ##STR80##              K.sub.1d   or                                     126b    "                    K.sub.2d   or                                     127a                                                                                 ##STR81##              K.sub.1d   o                                      127b    "                    K.sub.2d   0                                      128a                                                                                 ##STR82##              K.sub.1d   v                                      128b    "                    K.sub.2d   v                                      __________________________________________________________________________

Analogous dyestuffs may be prepared using the other coupling components listed in Table 1.

EXAMPLE 129

45 Parts of the dyestuff of Example 98 are dissolved in 500 parts water containing 3.4 parts glacial acetic acid. The resulting solution is evaporated to dryness, giving the dyestuff salt of the formula ##STR83## which has high solubility in cold water. Similarly, hydrochloric, sulphuric, phosphoric, formic and lactic acids may be used instead of acetic acid to give corresponding salts. The dyestuffs of the other examples may similarly be converted to salt forms.

EXAMPLE 130

80 Parts of the dyestuff salt of Example 129 are added to a solution of 20 parts dextrin and 20 parts glacial acetic acid in 500 parts water, and stirred to give a homogeneous suspension. Spray drying produces a blue-red granulate which is very soluble in water and which dyes paper in bluish-red shades.

The salt forms of the dyestuffs of the other examples may be converted to granulates in similar manner.

EXAMPLE 131

120 Parts of the dyestuff salt of Example 129 are added to a mixture of 150 parts butylpolyglycol, 50 parts glacial acetic acid and 600 parts water and dissolved by warming to 60°. The solution is filtered, cooled to room temperature and made up to 1000 parts with water. The resulting dye concentrate solution is storable for several months at room temperature and may be used directly or after dilution with water for dyeing paper in bluish-red shades.

Salts of the dyestuffs of the other examples may be similarly worked up into stable liquid dye preparations.

APPLICATION EXAMPLE A

70 Part of chemically bleached sulphite cellulose obtained from pinewood and 30 parts of chemically bleached sulphite cellulose obtained from birchwood are ground in 2000 part of water in a Hollander. 0.5 Parts of the dyestuff from Example 36 (as an acid addition salt, e.g. according to Example 129) are sprinkled into this pulp. Paper is produced from this pulp after mixing for 20 minutes. The absorbent paper which is obtained in this manner is dyed in a bluish-red shade. The waste water is practically colourless.

APPLICATION EXAMPLE B

0.5 Part of the dyestuff from Example 98 (as an acid addition salt, e.g. according to Example 129) are dissolved in 100 parts of hot water and cooled to room temperature. This solution is added to 100 parts of chemically bleached sulphite cellulose which have been ground in a Hollander with 2000 parts of water. Sizing takes place after thorough mixing for 15 minutes. The paper which is produced from this material has a bluish-red shade and good light- and wet-fastness.

APPLICATION EXAMPLE C

An absorbent length of unsized paper is drawn at 40°-50° through a dyestuff solution having the following composition:

0.5 parts of the dyestuff from Example 36 (as an acid addition salt, e.g. according to Example 129)

0.5 parts of starch and

99.0 parts of water.

The excess dyestuff solution is squeezed out through two rollers. The dried length of paper is dyed in a bluish-red shade.

The dyestuffs of the remaining examples may also be used for dyeing according to Application Examples A-C.

APPLICATION EXAMPLE D

100 Parts freshly tanned and neutralised chrome leather are agitated for 30 minutes in a vessel with a dyebath at 250 parts water at 55° and 0.5 part of the dyestuff of Example 98 in acid addition salt form, and then treated in the same bath for 30 minutes with 2 parts of an anionic fatty liquor based on sulphonated train oil. The leather is then dried and prepared in the normal way, giving a leather evenly dyed in a bluish-red shade.

Other low affinity vegetable-tanned leathers can similarly be dyed by known methods.

APPLICATION EXAMPLE E

2 Parts of the dyestuff of Example 98 in acid addition salt form are dissolved in 4000 parts demineralised water at 40°. 100 Parts of a cotton textile substrate are added, and the bath is raised to boiling point over 30 minutes and held at the boil for 1 hour. After rinsing and drying, a bluish-red dyeing is obtained having good light- and wet-fastness. The dye exhausts practically quantitatively, and the waste water is almost colourless. 

What is claimed is:
 1. A compound of the formula ##STR84## or an external salt thereof, wherein each R₁ ' is independently hydrogen or methyl,each R₈ is independently hydrogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, halo, C₁₋₄ alkylamino, di-(C₁₋₄ alkyl)amino, --SO₂ NR₁ R₁ or --CONR₁ R₁, wherein each R₁ is independently hydrogen or C₁₋₄ alkyl, each R₉ ' is independently hydrogen, chloro, methyl, methoxy, acetamido, benzamido, sulfamoyl or carbamoyl, each T_(b) is independently --NR₂ '--Q--NR₃ "R₄ " or --NR₂ '--Q--N.sup.⊕ R₅ "R₆ "R₇ ', whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl, each of R₅ " and R₆ " is independently C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " or R₅ " and R₆ " taken together and with the nitrogen atom to which they are joined form a piperidine or morpholine ring, R₇ ' is methyl, ethyl or benzyl, and Q is linear or branched C₂₋₆ alkylene, each T_(Ia) is independently --CO--T_(a) or --SO₂ --T_(a), wherein T_(a) is --NR₂ '--Q--NR₃ 'R₄ ' or --NR₂ '--Q--N.sup.⊕ R₅ 'R₆ 'R₇ ',wherein R₂ ' is hydrogen or methyl, each of R₃ ' and R₄ ' is independently hydrogen, C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl, each of R₅ ' and R₆ ' is independently C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl or R₃ ' and R₄ ' or R₅ ' and R₆ ' taken together and with the nitrogen atom to which they are joined form a pyrrolidine, piperidine or morpholine ring, R₇ ' is methyl, ethyl or benzyl, and Q is linear or branched C₂₋₆ alkylene, Z₃ is a divalent nitrogen-containing bridging radical, and Z₄ is 1,3-phenylene, 1,4-phenylene or ##STR85## wherein R₁₅ is hydrogen, chloro, methyl or methoxy, andZ₅ is a direct bond, --(CH₂)_(t) --, --O--, --O--(CH₂)_(t) --O--, --SO₂ --, --NHCO--, --NHCONH--, --NHCO--(CH₂)_(t) --CONH-- or --CONH--(CH₂)_(t) --NHCO--, wherein t is 2 or 3,with the provisos that (i) the number of basic groups and cationic groups together exceeds the number of sulfo groups, (ii) each basic group is independently in free base, internal salt or acid addition salt form, (iii) the positive charge of each cationic group is independently balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule or an external nonchromophoric anion, and (iv) the number of basic groups in internal salt form and cationic groups the positive charge of which is balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule does not exceed the number of sulfo groups present in the molecule.
 2. A compound according to claim 1 having the formula ##STR86## or an external salt thereof, wherein each R₈ is independently hydrogen, C₁₋₄ alkyl, C₁₋₄ alkoxy, halo, C₁₋₄ alkylamino, di-(C₁₋₄ alkyl)amino,--SO₂ NR₁ R₁ or --CONR₁ R₁, wherein each R₁ is independently hydrogen or C₁₋₄ alkyl,each T_(Ia) is independently --CO--T_(a) or --SO₂ T_(a),whereinT_(a) is --NR₂ '--Q--NR₃ 'R₄ ' or --N.sup.⊕ R₂ '--Q--NR₅ 'R₆ 'R₇ ', whereinR₂ ' is hydrogen or methyl, each of R₃ ' and R₄ ' is independently hydrogen, C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl, each of R₅ ' and R₆ ' is independently C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl or R₃ ' and R₄ ' or R₅ ' and R₆ ' taken together and with the nitrogen atom to which they are joined form a pyrrolidine, piperidine or morpholine ring, R₇ ' is methyl, ethyl or benzyl, and Q is linear or branched C₂₋₆ alkylene, and Z₃ is a divalent nitrogen-containing bridging radical, with the provisos that (i) the number of basic groups and cationic groups together exceeds the number of sulfo groups, (ii) each basic group is independently in free base, internal salt or acid addition salt form, (iii) the positive charge of each cationic group is independently balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule or an external nonchromophoric anion, and (iv) the maximum number of basic groups in internal salt form and cationic groups the positive charge of which is balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule does not exceed the number of sulfo groups present in the molecule.
 3. A compound according to claim 2, or an external salt thereof, whereineach of R₃ ' and R₄ ' is independently hydrogen, C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl, each of R₅ ' and R₆ ' is independently C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl or R₃ ' and R₄ ' or R₅ ' and R₆ ' taken together and with the nitrogen atom to which they are joined are pyrrolidino, piperidino or morpholino, and Z₃ is --NH--, --NHCONH--, --NHCOCH₂ CH₂ CONH--, ##STR87## wherein Y is chloro, hydroxy, --NR₂₁ R₂₂, C₅₋₆ cycloalkylamino, anilino or substituted anilino having, on the phenyl ring, 1 or 2 substituents selected from halo, C₁₋₄ alkyl, C₁₋₄ alkoxy, hydroxy and phenoxy, wherein each of R₂₁ and R₂₂ is independently hydrogen, C₁₋₄ alkyl or C₁₋₄ alkyl substituted by chloro, bromo, phenyl or hydroxy.
 4. A compound according to claim 3, or an external salt thereof, whereinthe two parts of the molecule joined by Z₃ are identical, and the four T_(Ia) groups are identical.
 5. A compound according to claim 4, or an external salt thereof, whereineach T_(Ia) is --CO--T_(a) or --SO₂ --T_(a), wherein T_(a) is --NR₂ '--Q--NR₃ 'R₄ ', whereinR₂ ' is hydrogen or methyl, each of R₃ ' and R₄ ' is independently hydrogen, C₁₋₆ alkyl, n-C₂₋₃ hydroxyalkyl or benzyl or R₃ ' and R₄ ' taken together and with the nitrogen atom to which they are joined are pyrrolidino, piperidino or morpholino, and Q is linear or branched C₂₋₆ alkylene.
 6. A compound according to claim 5, or an external salt thereof, whereineach R₈ is hydrogen, methyl, methoxy or chloro, and each T_(Ia) is --CO--X_(b) or --SO₂ --X_(b), whereinX_(b) is --NR₂ '--Q--NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and Q is linear or branched C₂₋₆ alkylene,with the proviso that the two T_(Ia) groups on each ring are in the 2,5- or 3,5-positions thereof.
 7. A compound according to claim 6, or an external salt thereof, whereineach T_(Ia) is --CO--NR₂ '--(CH₂)_(s) --NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and s is 2 to 6, inclusive, and Z₃ is --NHCONH--, --NHCOCH₂ CH₂ CONH--, ##STR88## wherein Y_(c) is chloro, amino or anilino.
 8. A compound according to claim 7, or an external salt thereof, whereineach R₈ is hydrogen, each T_(Ia) is --CO--NR₂ '--(CH₂)_(t) --NR₃ "'R₄ "', whereinR₂ ' is hydrogen or methyl, each of R₃ "' and R₄ "' is independently methyl or ethyl, and t is 2 or 3, and ##STR89## wherein Y_(c) is chloro, amino or anilino.
 9. A compound according to claim 8, or an external salt thereof, wherein each R₂ ' is hydrogen.
 10. An external salt according to claim 4 whereineach R₈ is hydrogen, and each T_(Ia) is --CO--NR₂ '--(CH₂)_(t) --N.sup.⊕ (CH₃)₃, whereinR₂ ' is hydrogen or methyl, and t is 2 or 3, and ##STR90## wherein Y_(c) is chloro, amino or anilino, with the proviso that the two T_(Ia) groups on each ring are in the 2,5- or 3,5-positions thereof.
 11. A compound according to claim 1 having the formula ##STR91## or an external salt thereof, wherein R₁ ' is independently hydrogen or methyl,each R₉ ' is independently hydrogen, chloro, methyl, methoxy, acetamido, benzamido, sulfamoyl or carbamoyl, each T_(b) is independently --NR₂ '--Q--NR₃ "R₄ " or --NR₂ '--Q--N.sup.⊕ R₅ "R₆ "R₇ ', whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl each of R₅ " and R₆ " is independently C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " or R₅ " and R₆ " taken together and with the nitrogen atom to which they are joined form a piperidine or morpholine ring, R₇ ' is methyl, ethyl or benzyl, and Q is linear or branched C₂₋₆ alkylene, and Z₃ is a divalent nitrogen-containing bridging radical,with the provisos that (i) the number of basic groups and cationic groups together exceeds the number of sulfo groups, (ii) each basic group is independently in free base, internal salt or acid addition salt form, (iii) the positive charge of each cationic group is independently balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule or an external nonchromophoric anion, and (iv) the maximum number of basic groups in internal salt form and cationic groups the positive charge of which is balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule does not exceed the number of sulfo groups present in the molecule.
 12. A compound according to claim 11, or an external salt thereof, whereineach of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl, each of R₅ " and R₆ " is independently C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " or R₅ " and R₆ " taken together with the nitrogen atom to which they are joined are piperidino or morpholino, and Z₃ is --NH--, --NHCONH--, --NHCOCH₂ CH₂ CONH--, ##STR92## wherein Y is chloro, hydroxy, --NR₂₁ R₂₂, C₅₋₆ cycloalkylamino, anilino or substituted anilino having, on the phenyl ring, 1 or 2 substituents selected from halo, C₁₋₄ alkyl, C₁₋₄ alkoxy, hydroxy and phenoxy, wherein each of R₂₁ and R₂₂ is independently hydrogen, C₁₋₄ alkyl or C₁₋₄ alkyl substituted by chloro, bromo, phenyl or hydroxy.
 13. A compound according to claim 12, or an external salt thereof, whereineach T_(b) is independently --NR₂ '--Q--NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and Q is linear or branched C₂₋₆ alkylene.
 14. A compound according to claim 13, or an external salt thereof, whereinR₉ ' is hydrogen, chloro, methyl, methoxy, acetamido or benzamido, each T_(b) is --NR₂ '--(CH₂)_(s) --NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and s is 2 to 6, inclusive, with the proviso that each ##STR93## group is meta or para to the --N═N-- radical, each sulfo group is in the 3-position and Z₃ is in the 6-position of each naphthalene ring, and the two parts of the molecule joined by Z₃ are identical.
 15. A compound according to claim 14, or an external salt thereof, wherein Z₃ is --NHCONH--, --NHCOCH₂ CH₂ CONH--, ##STR94## wherein Y_(c) is chloro, amino or anilino.
 16. A compound according to claim 15, or an external salt thereof, whereinR₉ ' is hydrogen, each T_(b) is --NR₂ '--(CH₂)_(t) --NR₃ "'R₄ "', whereinR₂ ' is hydrogen or methyl, each of R₃ "' and R₄ "' is independently methyl or ethyl, and t is 2 or 3, and ##STR95## wherein Y_(c) is chloro, amino or anilino.
 17. A compound according to claim 16, or an external salt thereof, whereineach R₁ ' is hydrogen, and each R₂ ' is hydrogen.
 18. The compound according to claim 17 having the formula ##STR96##
 19. The compound according to claim 15 having the formula ##STR97##
 20. An external salt according to claim 12 whereinR₉ ' is hydrogen, each T_(b) is --NR₂ '--(CH₂)_(t) --N.sup.⊕ (CH₃)₃, whereinR₂ ' is hydrogen or methyl, and t is 2 or 3, with the proviso that each ##STR98## group is meta or para to the --N═N-- radical, ##STR99## wherein Y_(c) is chloro, amino or anilino, each sulfo group is in the 3-position and Z₃ is in the 6-position of each naphthalene ring, and the two parts of the molecule joined by Z₃ are identical.
 21. A compound according to claim 1 having the formula ##STR100## or an external salt thereof, wherein each R₁ ' is independently hydrogen or methyl,each T_(b) is independently --NR₂ '--Q--NR₃ "R₄ " or --NR₂ '--Q--N.sup.⊕ R₅ "R₆ "R₇ ', whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl, each of R₅ " and R₆ " is independently C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " or R₅ " and R₆ " taken together and with the nitrogen atom to which they are joined form a piperidine or morpholine ring, and Q is linear or branched C₂₋₆ alkylene, and Z₄ is 1,3-phenylene, 1,4-phenylene or ##STR101## wherein R₁₅ is hydrogen, chloro, methyl or methoxy, andZ₅ is a direct bond, --(CH₂)_(t) --, --O--, --O--(CH₂)_(t) --O--, --SO₂ --, --NHCO--, --NHCONH--, --NHCO--(CH₂)_(t) --CONH-- or --CONH--(CH₂)_(t) --NHCO--, wherein t is 2 or 3,with the provisos that (i) each basic group is independently in free base, internal salt or acid addition salt form, (ii) the positive charge of each cationic group is independently balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule or an external non-chromophoric anion, and (iii) the maximum number of basic groups in internal salt form and cationic groups the positive charge of which is balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule is two.
 22. A compound according to claim 21, or an external salt thereof, whereineach T_(b) is independently --NR₂ '--Q--NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and Q is linear or branched C₂₋₆ alkylene.
 23. A compound according to claim 22 having the formula ##STR102## or an external salt thereof, wherein each R₁ ' is hydrogen or methyl,each X_(c) is independently --NR₂ '--(CH₂)_(s) --NR₃ "R₄ ", whereinR₂ ' is hydrogen or methyl, each of R₃ " and R₄ " is independently hydrogen, C₁₋₄ alkyl or hydroxyethyl or R₃ " and R₄ " taken together and with the nitrogen atom to which they are joined are piperidino or morpholino, and s is 2 to 6, inclusive, Z_(4a) is 1,3-phenylene, 1,4-phenylene, ##STR103## the two parts of the molecule joined by Z_(4a) are identical, with the proviso that each basic group is independently in free base, internal salt (maximum of two) or acid addition salt form.
 24. A compound according to claim 23, or an external salt thereof, whereineach X_(c) is independently --NR₂ '--(CH₂)_(t) --NR₃ "'R₄ "', whereinR₂ ' is hydrogen or methyl, each of R₃ "' and R₄ "' is independently methyl or ethyl, and t is 2 or
 3. 25. A compound according to claim 24, or an external salt thereof, whereineach R₁ ' is hydrogen, and each R₂ ' is hydrogen.
 26. The compound according to claim 22 having the formula ##STR104##
 27. The compound according to claim 22 having the formula ##STR105##
 28. The compound of having the formula ##STR106##
 29. The compound of having the formula ##STR107##
 30. An external salt according to claim 21 having the formula ##STR108## wherein each R₁ ' is hydrogen or methyl,each X_(e) is --NR₂ '--(CH₂)_(t) --N.sup.⊕ (CH₃)₃, whereinR₂ ' is hydrogen or methyl, and t is 2 or 3, Z_(4a) is 1,3-phenylene, 1,4-phenylene, ##STR109## the two parts of the molecule joined by Z_(4a) are identical, with the proviso that the positive charge of each cationic group is independently balanced by the negative charge of a --SO₃.sup.⊖ group of the molecule (maximum of two) or an external non-chromophoric anion.
 31. A method of dyeing a cellulosic substrate comprising applying thereto a compound according to claim 1 or an external salt thereof.
 32. A method of dyeing leather comprising applying thereto a compound according to claim 1 or an external salt thereof. 